Liquid crystal panels are is now establishing resolute position as displays based on research and development in recent years. However, frequent use of liquid crystal displays under bright lighting in monitors for car navigation and monitors for video cameras causes significant decrease in visibility by surface reflection. For this reason, polarizing plates equipped for these instruments necessarily requires antireflection layer treatment thereon. Polarizing plates having antireflection treatment performed thereto are used to almost all liquid crystal displays with high frequency of outdoor use. Moreover, ghost phenomena in outside environment of lighting light, such as fluorescent lamps, sunlight, and keyboarders, etc. being reflected on a screen, decreases visibility. For this reason, antiglare treatment is performed to polarizing plates.
In antireflection layer treatment, a design for reducing reflection of visible light region as much as possible is in general adopted in which a multilayered laminated layer, with two or more thin films, comprising materials having different refractive indexes is produced, using techniques, such as a vacuum deposition method, a sputtering method, and a CVD method. However, formation of a thin film in the above-mentioned dry treatment requires vacuum equipments, causing to high treatment expense. Therefore, recently, formation of antireflection layer in a wet coating method is usually performed. Usually, antireflection films have a configuration comprising a hard coat layer on a transparent base film, and furthermore an antireflection layer having a low refractive index. From a viewpoint of reflectance, a hard coat layer requires a higher refractive index, and an antireflection layer requires a lower refractive index. As lower refractive index materials, polymers including fluorine etc. are used from a viewpoint of refractive index or antifouling property (for example, refer to Japanese Patent Laid-Open No. 9-208898 official report).
However, although polymers including fluorine are very excellent in refractive index, formed films is very soft, and moreover, adhesion property with a hard coat resin layer is difficult to be secured. Therefore, there have been problems that scraping of the antireflection layer surface using polymers including fluorine with a cloth damages the surface. In order to solve the problems, investigated are a method of using siloxane based materials as a forming material of the antireflection layer, and a method in which an inorganic vapor deposition film with a thickness not more than a thickness of an optical film (antireflection layer) is prepared on the antireflection layer formed of polymers including fluorine. However, the above-mentioned methods cannot fully solve the problems because of higher reflectance caused by rise of refractive index, or of complicated manufacturing process.
The present invention aims at providing an antireflection film comprising an antireflection layer formed of low refractive index materials on a transparent base film, the antireflection film having outstanding antireflection characteristics and abrasion resistance, and a method for manufacturing the film.
Moreover, these invention aims at providing an antireflection film having excellent antireflection characteristics and abrasion resistance, and also excellent antiglare property.
Furthermore, this invention aim at providing a polarizing plate using the above-mentioned antireflection film, and an optical element, and furthermore aims at providing image viewing displays using them.